A muscle is a grouping of fibers that can contract and stretch to allow the body to move. The stretch reflex, also known as the myotatic reflex or the deep tendon reflex, is the body’s normal response to a lengthening of the muscles. When a muscle is stretched, a signal is sent from the spinal cord to the muscle instantaneously which makes the muscle tighten or contract. This protective reaction prevents the muscle from being stretched too far which could cause tearing of the muscle fibers and lead to dysfunction.
At the same moment the stretch reflex tenses the muscle being elongated, a signal is also sent to the opposing muscles, known as the antagonist muscles, to relax. For example, if the biceps or the muscles of the front of the upper arm are lengthened, the triceps in the back of the upper arm are loosened. This synchronized contraction and relaxation of coordinating muscle groups protect the area from being lengthened beyond the normal range of motion or extent of usual movement.
Though a normal response to lengthening of the muscles, the stretch reflex may also inhibit muscle flexibility and cause damage to the muscles when stretching techniques are poorly executed. Things like aggressive stretching by using too much force or pushing shortened muscles beyond their capabilities just because the muscle should be able to attain a certain position normally can potentially cause small rips or tears in the fibers. Not stretching before rigorous activity can also elevate the stretch reflex and increase the chances of injury.
Another source of muscle damage caused by the stretch reflex is improper stretching technique. Stretching the muscle quickly does not allow the coordinating tightening and relaxation of the lengthening muscles and its opposing muscles to adjust to a new position. Each stretch should be performed slowly until the stretch is felt. Bouncing during stretching may also cause muscle tearing as it may trick the protective stretch reflex and allow the body to push too far beyond its capabilities.
To reduce a strong stretch reflex and prevent damage to the muscles, stretching should be performed on a regular basis with emphasis on the muscle groups involved in specific activities. Stretching should be slow and controlled, and should never induce “pain”. The muscles should be lengthened until tenseness is felt and held there until the tightness diminishes. Once the involved muscles relax, attempts can be made to further the stretch. Continued attempts at stretching a muscle group in the proper manner will provide protection to the muscles and increase the overall flexibility of the fibers to allow for appropriate, pain-free movement.
